Storage virtual machine relocation

ABSTRACT

One or more techniques and/or devices are provided for storage virtual machine relocation (e.g., ownership change) between storage clusters. For example, operational statistics of a first storage cluster and a second storage cluster may be evaluated to identify a set of load balancing metrics. Ownership of one or more storage aggregates and/or one or more storage virtual machines may be changed (e.g., permanently changed for load balancing purposes or temporarily changed for disaster recovery purposes) between the first storage cluster and the second storage cluster utilizing zero-copy ownership change operations based upon the set of load balancing metrics. For example, if the first storage cluster is experiencing a relatively heavier load of client I/O operations and the second storage cluster has available resources, ownership of a storage aggregate and a storage virtual machine may be switched from the first storage cluster to the second storage cluster for load balancing.

BACKGROUND

A storage network environment may comprise one or more storage clustersof storage controllers (e.g., nodes) configured to provide clients withaccess to user data stored within storage devices. For example, a firststorage cluster may comprise a first storage controller hosting a firststorage virtual machine (e.g., a virtual server) configured to provideclients with access to user data stored, through a storage aggregate,across one or more storage devices owned by the first storage cluster. Asecond storage cluster may be configured according to a disasterrecovery relationship with respect to the first storage cluster, suchthat user data (e.g., client I/O operations may be split into two I/Ooperations that write user data to a local storage device at the firststorage cluster and mirror the user data to a remote storage device atthe second storage cluster so that two copies of user data aremaintained across storage clusters), configuration data (e.g., volumeinformation, a replication policy, a network interface configuration,etc.), and write caching data (e.g., data cached within a non-volatilerandom-access memory (NVRAM) of the first storage controller beforebeing written/flushed to a storage device during a consistency point)are replicated from the first storage cluster to the second storagecluster and vice versa. In this way, when a disaster occurs at the firststorage cluster and clients are unable to access user data within thefirst storage device because the first storage controller may beunavailable or may have failed from the disaster, a second storagecontroller of the second storage cluster may provide clients withfailover client access (e.g., a temporary switchover of ownership ofstorage devices and storage virtual machines) to replicated user datathat was replicated from the first storage device to a mirrored storagedevice accessible to the second storage controller. When the firststorage cluster recovers from the disaster, the second storage clustermay switch back (e.g., a switch back of ownership of the storage devicesand storage virtual machines) to the first storage cluster, such thatthe first storage controller provides clients with access to user datafrom the first storage device (e.g., the first storage device may besynchronized with any changes made to user data and/or configurationdata within the mirrored storage device during switchover operation bythe second storage controller). In this way, user data, cached data, andconfiguration data may be backed up between storage clusters fordisaster recovery.

A storage cluster may locally host multiple local storage virtualmachines that are actively providing clients with access to user data ofthe storage cluster. The storage virtual machines are replicated to aremote storage cluster, such that replicated storage virtual machines atthe remote storage cluster are dormant until a switchover occurs fromthe storage cluster to the remote storage cluster due to a failure ofthe storage cluster. The remote storage cluster may locally host virtualstorage machines that are actively providing clients with access to userdata of the remote storage cluster. Such storage virtual machines arereplicated to the storage cluster, such that replicated storage virtualmachines at the storage cluster are dormant until a switchover occursfrom the remote storage cluster to the storage cluster due to a failureof the remote storage cluster. Unfortunately, load balancing technologymay not exist for balancing workload between storage clusters of astorage network environment. Thus, if the storage cluster experiences arelatively higher load than the remote storage cluster, clients of thestorage cluster may experience increased latency and/or otherperformance issues.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a component block diagram illustrating an example clusterednetwork in accordance with one or more of the provisions set forthherein.

FIG. 2 is a component block diagram illustrating an example data storagesystem in accordance with one or more of the provisions set forthherein.

FIG. 3 is a flow chart illustrating an exemplary method of storagevirtual machine relocation between storage clusters.

FIG. 4A is a component block diagram illustrating an exemplary systemfor storage virtual machine relocation between storage clusters, where astorage virtual machine (A2) of a storage cluster (A) is providingclients with access to user data of a storage aggregate (A2).

FIG. 4B is a component block diagram illustrating an exemplary systemfor storage virtual machine relocation between storage clusters, whereownership of a second set of storage devices of a storage aggregate (A2)is switched from a storage cluster (A) to a storage cluster (B).

FIG. 4C is a component block diagram illustrating an exemplary systemfor storage virtual machine relocation between storage clusters, whereownership of a storage aggregate (A2) is switched from a storage cluster(A) to a storage cluster (B).

FIG. 4D is a component block diagram illustrating an exemplary systemfor storage virtual machine relocation between storage clusters, whereownership of a storage virtual machine (A2) and a replicated storagevirtual machine (A2-DR) are switched from a storage cluster (A) to astorage cluster (B) for load balancing.

FIG. 5A is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where a storage virtual machine (A2) of astorage cluster (A) is providing clients with access to user data of astorage aggregate (A2).

FIG. 5B is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where a storage cluster (A) experiences adisaster.

FIG. 5C is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where ownership of a second set ofstorage devices of a storage aggregate (A2) is switched from a storagecluster (A) to a storage cluster (B).

FIG. 5D is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where ownership of a storage aggregate(A2) is switched from a storage cluster (A) to a storage cluster (B).

FIG. 5E is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where a replicated storage virtualmachine (A2-DR) is switched from a dormant state to an active state.

FIG. 5F is a component block diagram illustrating an exemplary systemfor temporary storage virtual machine relocation between storageclusters at a storage virtual machine granularity in response to adisaster of a storage cluster, where a switchback operation is performedbased upon a storage cluster (A) recovering from a disaster.

FIG. 6 is an example of a computer readable medium in accordance withone or more of the provisions set forth herein.

DETAILED DESCRIPTION

Some examples of the claimed subject matter are now described withreference to the drawings, where like reference numerals are generallyused to refer to like elements throughout. In the following description,for purposes of explanation, numerous specific details are set forth inorder to provide an understanding of the claimed subject matter. It maybe evident, however, that the claimed subject matter may be practicedwithout these specific details. Nothing in this detailed description isadmitted as prior art.

One or more techniques and/or devices for storage virtual machinerelocation (e.g., a change in ownership) between storage clusters areprovided. Operational statistics (e.g., a number of client I/O requests,a current latency of processing client I/O requests, a latency ofperforming backup and replication functionality, an amount ofover-utilized or underutilized resources, etc.) of a first storagecluster and a second storage cluster are evaluated to identify a set ofload balancing metrics. For example, the set of load balancing metricsmay indicate that the first storage cluster has a first operational loadthat is a threshold amount greater than the second storage cluster(e.g., the second storage cluster may have more available resources forprocessing client I/O request, whereas the first storage cluster may beoverburdened with work). Accordingly, ownership of a first storageaggregate may be switched from the first storage cluster to the secondstorage cluster. Ownership of a storage virtual machine and a replicatedstorage virtual machine, configured to provide access to user datathrough the first storage aggregate, may be switched from the firststorage cluster to the second storage cluster. The replicated storagevirtual machine may be switched into an active state for facilitatingclient access, from the second storage cluster, to user data storedthrough the first storage aggregate.

In this way, ownership of storage aggregates and/or storage virtualmachines may be changed (e.g., permanently changed for load balancingpurposes or temporarily changed at a storage virtual machine granularityfor disaster recovery purposes) between the first storage cluster andthe second storage cluster, at a storage virtual machine granularity(e.g., merely a selected set of storage virtual machines may berelocated, such as having a change in ownership, based upon the loadbalancing metrics), utilizing zero-copy ownership change operations(e.g., ownership of the storage aggregate may be changed without copyingdata from the first storage cluster to the second storage clusterbecause client I/O operations for the first storage aggregate arealready mirrored between a local storage device of the first storagecluster and a remote mirror storage device of the second storage clusterduring processing of the client I/O operations) without disruptingclient access to user data.

To provide context for storage virtual machine relocation (e.g., achange in ownership) between storage clusters, FIG. 1 illustrates anembodiment of a clustered network environment 100 or a network storageenvironment. It may be appreciated, however, that the techniques, etc.described herein may be implemented within the clustered networkenvironment 100, a non-cluster network environment, and/or a variety ofother computing environments, such as a desktop computing environment.That is, the instant disclosure, including the scope of the appendedclaims, is not meant to be limited to the examples provided herein. Itwill be appreciated that where the same or similar components, elements,features, items, modules, etc. are illustrated in later figures but werepreviously discussed with regard to prior figures, that a similar (e.g.,redundant) discussion of the same may be omitted when describing thesubsequent figures (e.g., for purposes of simplicity and ease ofunderstanding).

FIG. 1 is a block diagram illustrating an example clustered networkenvironment 100 that may implement at least some embodiments of thetechniques and/or systems described herein. The example environment 100comprises data storage systems or storage sites 102 and 104 that arecoupled over a cluster fabric 106, such as a computing network embodiedas a private Infiniband, Fibre Channel (FC), or Ethernet networkfacilitating communication between the storage systems 102 and 104 (andone or more modules, component, etc. therein, such as, nodes 116 and118, for example). It will be appreciated that while two data storagesystems 102 and 104 and two nodes 116 and 118 are illustrated in FIG. 1,that any suitable number of such components is contemplated. In anexample, nodes 116, 118 comprise storage controllers (e.g., node 116 maycomprise a primary or local storage controller and node 118 may comprisea secondary or remote storage controller) that provide client devices,such as host devices 108, 110, with access to data stored within datastorage devices 128, 130. Similarly, unless specifically providedotherwise herein, the same is true for other modules, elements,features, items, etc. referenced herein and/or illustrated in theaccompanying drawings. That is, a particular number of components,modules, elements, features, items, etc. disclosed herein is not meantto be interpreted in a limiting manner.

It will be further appreciated that clustered networks are not limitedto any particular geographic areas and can be clustered locally and/orremotely. Thus, in one embodiment a clustered network can be distributedover a plurality of storage systems and/or nodes located in a pluralityof geographic locations; while in another embodiment a clustered networkcan include data storage systems (e.g., 102, 104) residing in a samegeographic location (e.g., in a single onsite rack of data storagedevices).

In the illustrated example, one or more host devices 108, 110 which maycomprise, for example, client devices, personal computers (PCs),computing devices used for storage (e.g., storage servers), and othercomputers or peripheral devices (e.g., printers), are coupled to therespective data storage systems 102, 104 by storage network connections112, 114. Network connection may comprise a local area network (LAN) orwide area network (WAN), for example, that utilizes Network AttachedStorage (NAS) protocols, such as a Common Internet File System (CIFS)protocol or a Network File System (NFS) protocol to exchange datapackets. Illustratively, the host devices 108, 110 may begeneral-purpose computers running applications, and may interact withthe data storage systems 102, 104 using a client/server model forexchange of information. That is, the host device may request data fromthe data storage system (e.g., data on a storage device managed by anetwork storage control configured to process I/O commands issued by thehost device for the storage device), and the data storage system mayreturn results of the request to the host device via one or more networkconnections 112, 114.

The nodes 116, 118 on clustered data storage systems 102, 104 cancomprise network or host nodes that are interconnected as a cluster toprovide data storage and management services, such as to an enterprisehaving remote locations, cloud storage (e.g., a storage endpoint may bestored within a data cloud), etc., for example. Such a node in a datastorage and management network cluster environment 100 can be a deviceattached to the network as a connection point, redistribution point orcommunication endpoint, for example. A node may be capable of sending,receiving, and/or forwarding information over a network communicationschannel, and could comprise any device that meets any or all of thesecriteria. One example of a node may be a data storage and managementserver attached to a network, where the server can comprise a generalpurpose computer or a computing device particularly configured tooperate as a server in a data storage and management system.

In an example, a first cluster of nodes such as the nodes 116, 118(e.g., a first set of storage controllers configured to provide accessto a first storage aggregate comprising a first logical grouping of oneor more storage devices) may be located on a first storage site. Asecond cluster of nodes, not illustrated, may be located at a secondstorage site (e.g., a second set of storage controllers configured toprovide access to a second storage aggregate comprising a second logicalgrouping of one or more storage devices). The first cluster of nodes andthe second cluster of nodes may be configured according to a disasterrecovery configuration where a surviving cluster of nodes providesswitchover access to storage devices of a disaster cluster of nodes inthe event a disaster occurs at a disaster storage site comprising thedisaster cluster of nodes (e.g., the first cluster of nodes providesclient devices with switchover data access to storage devices of thesecond storage aggregate in the event a disaster occurs at the secondstorage site).

As illustrated in the exemplary environment 100, nodes 116, 118 cancomprise various functional components that coordinate to providedistributed storage architecture for the cluster. For example, the nodescan comprise a network module 120, 122 and a data module 124, 126.Network modules 120, 122 can be configured to allow the nodes 116, 118(e.g., network storage controllers) to connect with host devices 108,110 over the network connections 112, 114, for example, allowing thehost devices 108, 110 to access data stored in the distributed storagesystem. Further, the network modules 120, 122 can provide connectionswith one or more other components through the cluster fabric 106. Forexample, in FIG. 1, a first network module 120 of first node 116 canaccess a second data storage device 130 by sending a request through asecond data module 126 of a second node 118.

Data modules 124, 126 can be configured to connect one or more datastorage devices 128, 130, such as disks or arrays of disks, flashmemory, or some other form of data storage, to the nodes 116, 118. Thenodes 116, 118 can be interconnected by the cluster fabric 106, forexample, allowing respective nodes in the cluster to access data on datastorage devices 128, 130 connected to different nodes in the cluster.Often, data modules 124, 126 communicate with the data storage devices128, 130 according to a storage area network (SAN) protocol, such asSmall Computer System Interface (SCSI) or Fiber Channel Protocol (FCP),for example. Thus, as seen from an operating system on a node 116, 118,the data storage devices 128, 130 can appear as locally attached to theoperating system. In this manner, different nodes 116, 118, etc. mayaccess data blocks through the operating system, rather than expresslyrequesting abstract files.

It should be appreciated that, while the example embodiment 100illustrates an equal number of network and data modules, otherembodiments may comprise a differing number of these modules. Forexample, there may be a plurality of network and data modulesinterconnected in a cluster that does not have a one-to-onecorrespondence between the network and data modules. That is, differentnodes can have a different number of network and data modules, and thesame node can have a different number of network modules than datamodules.

Further, a host device 108, 110 can be networked with the nodes 116, 118in the cluster, over the networking connections 112, 114. As an example,respective host devices 108, 110 that are networked to a cluster mayrequest services (e.g., exchanging of information in the form of datapackets) of a node 116, 118 in the cluster, and the node 116, 118 canreturn results of the requested services to the host devices 108, 110.In one embodiment, the host devices 108, 110 can exchange informationwith the network modules 120, 122 residing in the nodes (e.g., networkhosts) 116, 118 in the data storage systems 102, 104.

In one embodiment, the data storage devices 128, 130 comprise volumes132, which is an implementation of storage of information onto diskdrives or disk arrays or other storage (e.g., flash) as a file-systemfor data, for example. Volumes can span a portion of a disk, acollection of disks, or portions of disks, for example, and typicallydefine an overall logical arrangement of file storage on disk space inthe storage system. In one embodiment a volume can comprise stored dataas one or more files that reside in a hierarchical directory structurewithin the volume.

Volumes are typically configured in formats that may be associated withparticular storage systems, and respective volume formats typicallycomprise features that provide functionality to the volumes, such asproviding an ability for volumes to form clusters. For example, where afirst storage system may utilize a first format for their volumes, asecond storage system may utilize a second format for their volumes.

In the example environment 100, the host devices 108, 110 can utilizethe data storage systems 102, 104 to store and retrieve data from thevolumes 132. In this embodiment, for example, the host device 108 cansend data packets to the network module 120 in the node 116 within datastorage system 102. The node 116 can forward the data to the datastorage device 128 using the data module 124, where the data storagedevice 128 comprises volume 132A. In this way, in this example, the hostdevice can access the storage volume 132A, to store and/or retrievedata, using the data storage system 102 connected by the networkconnection 112. Further, in this embodiment, the host device 110 canexchange data with the network module 122 in the host 118 within thedata storage system 104 (e.g., which may be remote from the data storagesystem 102). The host 118 can forward the data to the data storagedevice 130 using the data module 126, thereby accessing volume 132Bassociated with the data storage device 130.

It may be appreciated that storage virtual machine relocation (e.g., achange in ownership) between storage clusters may be implemented withinthe clustered network environment 100. For example, a relocationcomponent may be implemented for the node 116 and/or the node 118. Therelocation component may be configured to relocate a storage virtualmachine between the node 116 and the node 118, where the node 116 ishosted within a first storage cluster and the node 118 is hosted withina second storage cluster. In this way, storage virtual machines may bepermanently relocated, at a storage virtual machine granularity, betweenstorage clusters utilizing zero-copy ownership change operations forload balancing without client interruption to user data. It may beappreciated that storage virtual machine relocation may be implementedfor and/or between any type of computing environment, and may betransferrable between physical devices (e.g., node 116, node 118, etc.)and/or a cloud computing environment (e.g., remote to the clusterednetwork environment 100).

FIG. 2 is an illustrative example of a data storage system 200 (e.g.,102, 104 in FIG. 1), providing further detail of an embodiment ofcomponents that may implement one or more of the techniques and/orsystems described herein. The example data storage system 200 comprisesa node 202 (e.g., host nodes 116, 118 in FIG. 1), and a data storagedevice 234 (e.g., data storage devices 128, 130 in FIG. 1). The node 202may be a general purpose computer, for example, or some other computingdevice particularly configured to operate as a storage server. A hostdevice 205 (e.g., 108, 110 in FIG. 1) can be connected to the node 202over a network 216, for example, to provides access to files and/orother data stored on the data storage device 234. In an example, thenode 202 comprises a storage controller that provides client devices,such as the host device 205, with access to data stored within datastorage device 234.

The data storage device 234 can comprise mass storage devices, such asdisks 224, 226, 228 of a disk array 218, 220, 222. It will beappreciated that the techniques and systems, described herein, are notlimited by the example embodiment. For example, disks 224, 226, 228 maycomprise any type of mass storage devices, including but not limited tomagnetic disk drives, flash memory, and any other similar media adaptedto store information, including, for example, data (D) and/or parity (P)information.

The node 202 comprises one or more processors 204, a memory 206, anetwork adapter 210, a cluster access adapter 212, and a storage adapter214 interconnected by a system bus 242. The storage system 200 alsoincludes an operating system 208 installed in the memory 206 of the node202 that can, for example, implement a Redundant Array of Independent(or Inexpensive) Disks (RAID) optimization technique to optimize areconstruction process of data of a failed disk in an array.

The operating system 208 can also manage communications for the datastorage system, and communications between other data storage systemsthat may be in a clustered network, such as attached to a cluster fabric215 (e.g., 106 in FIG. 1). Thus, the node 202, such as a network storagecontroller, can respond to host device requests to manage data on thedata storage device 234 (e.g., or additional clustered devices) inaccordance with these host device requests. The operating system 208 canoften establish one or more file systems on the data storage system 200,where a file system can include software code and data structures thatimplement a persistent hierarchical namespace of files and directories,for example. As an example, when a new data storage device (not shown)is added to a clustered network system, the operating system 208 isinformed where, in an existing directory tree, new files associated withthe new data storage device are to be stored. This is often referred toas “mounting” a file system.

In the example data storage system 200, memory 206 can include storagelocations that are addressable by the processors 204 and adapters 210,212, 214 for storing related software application code and datastructures. The processors 204 and adapters 210, 212, 214 may, forexample, include processing elements and/or logic circuitry configuredto execute the software code and manipulate the data structures. Theoperating system 208, portions of which are typically resident in thememory 206 and executed by the processing elements, functionallyorganizes the storage system by, among other things, invoking storageoperations in support of a file service implemented by the storagesystem. It will be apparent to those skilled in the art that otherprocessing and memory mechanisms, including various computer readablemedia, may be used for storing and/or executing application instructionspertaining to the techniques described herein. For example, theoperating system can also utilize one or more control files (not shown)to aid in the provisioning of virtual machines.

The network adapter 210 includes the mechanical, electrical andsignaling circuitry needed to connect the data storage system 200 to ahost device 205 over a computer network 216, which may comprise, amongother things, a point-to-point connection or a shared medium, such as alocal area network. The host device 205 (e.g., 108, 110 of FIG. 1) maybe a general-purpose computer configured to execute applications. Asdescribed above, the host device 205 may interact with the data storagesystem 200 in accordance with a client/host model of informationdelivery.

The storage adapter 214 cooperates with the operating system 208executing on the node 202 to access information requested by the hostdevice 205 (e.g., access data on a storage device managed by a networkstorage controller). The information may be stored on any type ofattached array of writeable media such as magnetic disk drives, flashmemory, and/or any other similar media adapted to store information. Inthe example data storage system 200, the information can be stored indata blocks on the disks 224, 226, 228. The storage adapter 214 caninclude input/output (I/O) interface circuitry that couples to the disksover an I/O interconnect arrangement, such as a storage area network(SAN) protocol (e.g., Small Computer System Interface (SCSI), iSCSI,hyperSCSI, Fiber Channel Protocol (FCP)). The information is retrievedby the storage adapter 214 and, if necessary, processed by the one ormore processors 204 (or the storage adapter 214 itself) prior to beingforwarded over the system bus 242 to the network adapter 210 (and/or thecluster access adapter 212 if sending to another node in the cluster)where the information is formatted into a data packet and returned tothe host device 205 over the network connection 216 (and/or returned toanother node attached to the cluster over the cluster fabric 215).

In one embodiment, storage of information on arrays 218, 220, 222 can beimplemented as one or more storage “volumes” 230, 232 that are comprisedof a cluster of disks 224, 226, 228 defining an overall logicalarrangement of disk space. The disks 224, 226, 228 that comprise one ormore volumes are typically organized as one or more groups of RAIDs. Asan example, volume 230 comprises an aggregate of disk arrays 218 and220, which comprise the cluster of disks 224 and 226.

In one embodiment, to facilitate access to disks 224, 226, 228, theoperating system 208 may implement a file system (e.g., write anywherefile system) that logically organizes the information as a hierarchicalstructure of directories and files on the disks. In this embodiment,respective files may be implemented as a set of disk blocks configuredto store information, whereas directories may be implemented asspecially formatted files in which information about other files anddirectories are stored.

Whatever the underlying physical configuration within this data storagesystem 200, data can be stored as files within physical and/or virtualvolumes, which can be associated with respective volume identifiers,such as file system identifiers (FSIDs), which can be 32-bits in lengthin one example.

A physical volume corresponds to at least a portion of physical storagedevices whose address, addressable space, location, etc. doesn't change,such as at least some of one or more data storage devices 234 (e.g., aRedundant Array of Independent (or Inexpensive) Disks (RAID system)).Typically the location of the physical volume doesn't change in that the(range of) address(es) used to access it generally remains constant.

A virtual volume, in contrast, is stored over an aggregate of disparateportions of different physical storage devices. The virtual volume maybe a collection of different available portions of different physicalstorage device locations, such as some available space from each of thedisks 224, 226, and/or 228. It will be appreciated that since a virtualvolume is not “tied” to any one particular storage device, a virtualvolume can be said to include a layer of abstraction or virtualization,which allows it to be resized and/or flexible in some regards.

Further, a virtual volume can include one or more logical unit numbers(LUNs) 238, directories 236, Qtrees 235, and files 240. Among otherthings, these features, but more particularly LUNS, allow the disparatememory locations within which data is stored to be identified, forexample, and grouped as data storage unit. As such, the LUNs 238 may becharacterized as constituting a virtual disk or drive upon which datawithin the virtual volume is stored within the aggregate. For example,LUNs are often referred to as virtual drives, such that they emulate ahard drive from a general purpose computer, while they actually comprisedata blocks stored in various parts of a volume.

In one embodiment, one or more data storage devices 234 can have one ormore physical ports, wherein each physical port can be assigned a targetaddress (e.g., SCSI target address). To represent respective volumesstored on a data storage device, a target address on the data storagedevice can be used to identify one or more LUNs 238. Thus, for example,when the node 202 connects to a volume 230, 232 through the storageadapter 214, a connection between the node 202 and the one or more LUNs238 underlying the volume is created.

In one embodiment, respective target addresses can identify multipleLUNs, such that a target address can represent multiple volumes. The I/Ointerface, which can be implemented as circuitry and/or software in thestorage adapter 214 or as executable code residing in memory 206 andexecuted by the processors 204, for example, can connect to volume 230by using one or more addresses that identify the LUNs 238.

It may be appreciated that storage virtual machine relocation (e.g.,change in ownership) between storage clusters may be implemented for thedata storage system 200. For example, a relocation component may beimplemented for the node 202 of a first storage cluster and a secondnode of a second storage cluster. The relocation component may beconfigured to relocate a storage virtual machine between the node 202and the second node. In this way, storage virtual machines may bepermanently relocated, at a storage virtual machine granularity, betweenstorage clusters utilizing zero-copy ownership change operations forload balancing without client interruption to user data. It may beappreciated that storage virtual machine relocation may be implementedfor and/or between any type of computing environment, and may betransferrable between physical devices (e.g., node 202, host 205, etc.)and/or a cloud computing environment (e.g., remote to the node 202and/or the host 205).

One embodiment of storage virtual machine relocation (e.g., change inownership) between storage clusters is illustrated by an exemplarymethod 300 of FIG. 3. At 302, operational statistics of a first storagecluster and a second storage cluster are evaluated to determine that thefirst storage cluster has a first operational load and that the secondstorage cluster has a second operational load. An operational load maycorrespond to a load on a storage cluster in relation to resources ofthe storage cluster (e.g., a latency of processing client I/Ooperations, available hardware resources of storage controllers,bandwidth, etc.). The first storage cluster may comprise a first storagevirtual machine associated with a first storage aggregate, a secondstorage virtual machine associated with a second storage aggregate,and/or other storage virtual machines associated with other storageaggregates. The storage virtual machines, hosted by the first storagecluster, may be replicated (configuration data replicated using aconfiguration replication layer, cached data of an NVRAM replicatedusing NVRAM mirroring, etc.) to the second storage cluster as replicatedstorage virtual machines located at the second storage cluster butinitially owned by the first storage cluster. The storage virtualmachines may be in an active state for facilitating client access touser data within the storage aggregates of the first storage cluster,and the replicated virtual machines may be in a dormant state waiting toprovide failover client access to user data in the event the firststorage cluster fails or has a disaster.

A storage aggregate may be stored across one or more storage devicesaccording to a data mirroring configuration. A RAID synchronousmirroring solution may be implemented where a client I/O operation tothe storage aggregate is split into two operations where data is storedwithin a local storage device of a local storage cluster by a firstoperation and a backup mirror of the data is stored within a remotemirror storage device of a remote storage cluster. For example, a writeoperation to the first storage aggregate may be split into a firstoperation that stores data of the write operation within a first storagedevice of the first storage cluster (e.g., during a flush of an NVRAM,within which the data of the write operation may have been cached, ofthe first storage controller into a local storage device) and within amirror storage device of the second storage cluster. In this way, datawithin the first storage aggregate may be stored within the firststorage cluster and mirrored to the second storage cluster.

The first operational load may be compared to the second operationalload to determine whether the first storage cluster and/or the secondstorage cluster are overburdened with workloads or have availableresources. For example, the first operational load may be determined asbeing a threshold amount greater than the second operational load, andthus load balancing of workloads from the first storage cluster to thesecond storage cluster may be beneficial. Accordingly, ownership of thefirst storage aggregate may be switched from the first storage clusterto the second storage cluster, at 304. For example, the first storageaggregate may be unmounted. Ownership of a first storage device,associated with the first storage aggregate and maintained at the firststorage cluster, may be changed from the first storage cluster to thesecond storage cluster. In an example, ownership of a mirror storagedevice, associated with the first storage aggregate as a mirror of thefirst storage aggregate and maintained at the second storage cluster,may be changed from the first storage cluster to the second storagecluster. The first storage aggregate may be onlined for ownership by thesecond storage cluster. A zero-copy ownership change operation may beperformed to switch the ownership of the first storage aggregate becausethe mirror storage device, hosted at the second storage cluster, is abackup mirror already comprising replicated data of the first storagedevice, and thus little to no additional copying of user data to thesecond storage cluster may be performed, for example. In an example, thesecond storage cluster may be specified as a non-temporary owner (e.g.,a permanent owner) of the first storage aggregate.

At 306, ownership of the first storage virtual machine and thereplicated storage virtual machine may be switched from the firststorage cluster to the second storage cluster. At 308, the replicatedstorage virtual machine may be switched to an active state forfacilitating client access, from the second storage cluster, to userdata stored through the first storage aggregate (e.g., replicated datastored within the mirror storage device). The first storage virtualmachine may be switch to a dormant state. In an example, the secondstorage cluster may be designated as a non-temporary owner (e.g., apermanent owner) of the first storage virtual machine. Non-disruptiveclient access to data may be maintained through the first storageaggregate during switchover of ownership of the first storage aggregate,the first storage virtual machine, and/or the replicated storage virtualmachine from the first storage cluster to the second storage cluster. Inthis way, ownership of one or more storage aggregates and one or morestorage virtual machines may be permanently changed between the firststorage cluster and the second storage cluster utilizing zero-copyownership change operations based upon load balancing metrics associatedwith the first storage cluster and the second storage cluster withoutdisrupting client access to user data.

In an example, storage virtual machines may be temporarily relocatedbetween storage clusters at a storage virtual machine granularity suchas for disaster recovery purposes. For example, the first storagecluster and the second storage cluster may be configured according to adisaster recovery relationship, such that the second storage cluster isconfigured to provide failover client access to data, replicated fromthe first storage cluster (e.g., access to data within a mirror storagedevice, of the second storage cluster, comprising replicated datamirrored from a storage device of the first storage cluster), responsiveto a disaster occurring at the first storage cluster. The first storagecluster may comprise a third storage aggregate and a third storagevirtual machine. The second storage cluster may comprise a replicatedthird storage virtual machine that is a replication of the third storagevirtual machine.

Responsive to determining that the first storage cluster has experiencedthe disaster, a temporary switchover of ownership of the third storageaggregate, but not the second storage aggregate, may be performed fromthe first storage cluster to the second storage cluster based upon thedisaster recovery relationship. For example, the first storage clustermay retain ownership of the third storage virtual machine and thereplicated storage virtual machine, however, the replicated storagevirtual machine may be switched from a dormant state to an active statefor providing failover client access to the third storage aggregatetemporarily owned by the second storage cluster. In this way, selectstorage aggregates may be temporarily relocated, at a storage virtualserver granularity, for disaster recovery operation.

Responsive to determining that the first storage cluster has recoveredto an operational state from the disaster, a switchback of ownership ofthe third storage aggregate may be performed from the second storagecluster to the first storage cluster. The third replicated storagevirtual machine may be switched from the active state to the dormantstate. The storage virtual machine may be set to the active state forproviding primary client access to data from the third storageaggregate.

FIGS. 4A-4D illustrate examples of a system 400, comprising a relocationcomponent 401, for storage virtual machine relocation (e.g., change inownership) between storage clusters. The relocation component 401 may behosted within storage cluster (A) 402, storage cluster (B) 404, or aremote location having network connectivity to the storage cluster (A)402 and/or the storage cluster (B) 404. The storage cluster (A) 402 maycomprise a storage controller (A1) 406, a storage controller (A2) 416,and/or other storage controllers not illustrated. The storage cluster(B) 404 may comprise a storage controller (B1) 418, a storage controller(B2) 426, and/or other storage controllers not illustrated. It may beappreciated that storage controllers and storage devices that are ownedby the storage cluster (A) 402 are represented by a dotted fill, whilestorage controllers and storage devices that are owned by the storagecluster (B) 404 are represented by a slanted line fill.

A storage controller may be configured to provide clients with storageusing storage aggregates hosted by storage virtual machines. In anexample, the storage controller (A1) 406 may provide clients withstorage through a storage aggregate (A1) maintained by a storage virtualmachine (A1) 408. The storage aggregate (A1) may comprise a first set ofstorage devices 430 (e.g., one or more storage devices hosted within thestorage cluster (A) 402 and one or more mirrored storage devices hostedwithin the storage cluster (B) 404, such that a client I/O operation tothe storage aggregate (A1) is written to both a storage device hostedwithin the storage cluster (A) 402 and a corresponding mirrored storagedevice hosted within the storage cluster (B) 404 for data redundancy anddata loss mitigation). In another example, the storage controller (A2)426 may provide clients with storage through a storage aggregate (A2)maintained by a storage virtual machine (A2) 414. The storage aggregate(A2) may comprise a second set of storage devices 434 (e.g., one or morestorage devices hosted within the storage cluster (A) 402 and one ormore mirrored storage devices hosted within the storage cluster (B) 404,such that a client I/O operation to the storage aggregate (A2) iswritten to both a storage device hosted within the storage cluster (A)402 and a corresponding mirrored storage device hosted within thestorage cluster (B) 404 for data redundancy and data loss mitigation).

In another example, the storage controller (B1) 418 may provide clientswith storage through a storage aggregate (B1) maintained by a storagevirtual machine (B1) 422. The storage aggregate (B1) may comprise athird set of storage devices 432 (e.g., one or more storage deviceshosted within the storage cluster (B) 404 and one or more mirroredstorage devices hosted within the storage cluster (A) 402, such that aclient I/O operation to the storage aggregate (B1) is written to both astorage device hosted within the storage cluster (B) 404 and acorresponding mirrored storage device hosted within the storage cluster(A) 402 for data redundancy and data loss mitigation).

Replicated storage virtual machines, corresponding to replications ofstorage virtual machines at a different storage cluster, may bemaintained at remote storage clusters in order to provide failoveraccess to replicated user data in the event a disaster occurs at astorage cluster. For example, the storage cluster (B) 404 may host areplicated storage virtual machine (A1-DR) 420, corresponding to areplication of the storage virtual machine (A1) 408, and a replicatedstorage virtual machine (A2-DR) 424 corresponding to a replication ofthe storage virtual machine (A2) 414, which may provide failover accessto replicated user data in the event the storage cluster (A) 402experiences a disaster. The storage cluster (A) 402 may host areplicated storage virtual machine (B1-DR) 410 corresponding to areplication of the storage virtual machine (B1) 422, which may providefailover access to replicated user data in the event the storage cluster(B) 404 experiences a disaster. Within a pairing of storage virtualmachines, merely a single storage virtual machine is active forproviding access to user data while the other storage virtual machine isdormant (e.g., the replicated storage virtual machine (A1-DR) 420 isdormant while the storage virtual machine (A1) 408 is actively providingclients with access to user data).

FIG. 4A illustrates the storage virtual machine (A2) 414 activelyserving clients with access to user data of the storage aggregate (A2)stored within the second set of storage devices 434 (e.g., from withinstorage devices hosted at the storage cluster (A) 402, and where data isreplicated to mirrored storage devices hosted at the storage cluster (B)404) while the storage cluster (A) 402 has ownership 440 of the secondset of storage devices 434 and the storage aggregate (A2). Therelocation component 401 may evaluate operational statistics of thestorage cluster (A) 402 and the storage cluster (B) 404 to determinethat an operational load of the storage cluster (A) 402 exceeds anoperational load to the storage cluster (B) 404 by a threshold amount(e.g., latency, available resources, bandwidth, a number of clientsbeing served, a number and frequency of client I/O operations, and/orother information may indicate that the storage cluster (B) 404 has moreavailable resources and/or a lighter load than the storage cluster (A)402). Accordingly, the relocation component 401 may perform a relocation(e.g., a change in ownership) of the storage virtual machine (A2) 414from the storage cluster (A) 402 to the storage cluster (B) 404 for loadbalancing.

FIG. 4B illustrates the relocation component 401 performing therelocation by initiating a switch of ownership 440B of the second set ofstorage devices 434 of the storage aggregate (A2) from the storagecluster (A) 402 to the storage cluster (B) 404. FIG. 4C illustrates therelocation component 401 switching ownership of the storage aggregate(A2) from the storage cluster (A) 402 to the storage cluster (B) 404,which is illustrated by the second set of storage devices 434 having theslanted line fill, as opposed to the dotted fill, to illustrateownership by the storage cluster (B) 404.

FIG. 4D illustrates the relocation component 401 switching ownership ofthe storage virtual machine (A2) 414 and the replicated storage virtualmachine (A2-DR) 424 from the storage cluster (A) 402 to the storagecluster (B) 404. The relocation component 401 may switch the storagevirtual machine 414 into a dormant state and the replicated storagevirtual machine (A2-DR) 424 into an active state for facilitating clientaccess, from the storage cluster (B) 404, to user data stored within thestorage aggregate (A2) such as data within the second set of storagedevices 434 now owned by the storage cluster (B) 404. In this way, loadbalancing may be achieved between the storage cluster (A) 402 and thestorage cluster (B) 404 at a storage virtual machine granularity (e.g.,resources of the storage controller (B2) 426 may now be used to host thereplicated storage virtual machine (A2-DR) 424 in the active state).

FIGS. 5A-5F illustrate examples of a system 500, comprising a relocationcomponent 501, for temporary storage virtual machine relocation betweenstorage clusters at a storage virtual machine granularity in response toa disaster of a storage cluster. The relocation component 501 may behosted within storage cluster (A) 502, storage cluster (B) 504, or aremote location having network connectivity to the storage cluster (A)502 and/or the storage cluster (B) 504. The storage cluster (A) 502 maycomprise a storage controller (A1) 506, a storage controller (A2) 516,and/or other storage controllers not illustrated. The storage cluster(B) 504 may comprise a storage controller (B1) 518, a storage controller(B2) 526, and/or other storage controllers not illustrated. It may beappreciated that storage controllers and storage devices that are ownedby the storage cluster (A) 502 are represented by a dotted fill, whilestorage controllers and storage devices that are owned by the storagecluster (B) 504 are represented by a slanted line fill.

A storage controller may be configured to provide clients with storageusing storage aggregates hosted by storage virtual machines. In anexample, the storage controller (A1) 506 may provide clients withstorage through a storage aggregate (A1) maintained by a storage virtualmachine (A1) 508. The storage aggregate (A1) may comprise a first set ofstorage devices 530 (e.g., one or more storage devices hosted within thestorage cluster (A) 502 and one or more mirrored storage devices hostedwithin the storage cluster (B) 504, such that a client I/O operation tothe storage aggregate (A1) is written to both a storage device hostedwithin the storage cluster (A) 502 and a corresponding mirrored storagedevice hosted within the storage cluster (B) 504 for data redundancy anddata loss mitigation). In another example, the storage controller (A2)526 may provide clients with storage through a storage aggregate (A2)maintained by a storage virtual machine (A2) 514. The storage aggregate(A2) may comprise a second set of storage devices 534 (e.g., one or morestorage devices hosted within the storage cluster (A) 502 and one ormore mirrored storage devices hosted within the storage cluster (B) 504,such that a client I/O operation to the storage aggregate (A2) iswritten to both a storage device hosted within the storage cluster (A)502 and a corresponding mirrored storage device hosted within thestorage cluster (B) 504 for data redundancy and data loss mitigation).

In another example, the storage controller (B1) 518 may provide clientswith storage through a storage aggregate (B1) maintained by a storagevirtual machine (B1) 522. The storage aggregate (B1) may comprise athird set of storage devices 532 (e.g., one or more storage deviceshosted within the storage cluster (B) 504 and one or more mirroredstorage devices hosted within the storage cluster (A) 502, such that aclient I/O operation to the storage aggregate (B1) is written to both astorage device hosted within the storage cluster (B) 504 and acorresponding mirrored storage device hosted within the storage cluster(A) 502 for data redundancy and data loss mitigation).

Replicated storage virtual machines, corresponding to replications ofstorage virtual machines at a different storage cluster, may bemaintained at remote storage clusters in order to provide failoveraccess to replicated user data in the event a disaster occurs at astorage cluster. For example, the storage cluster (B) 504 may host areplicated storage virtual machine (A1-DR) 520, corresponding to areplication of the storage virtual machine (A1) 508, and a replicatedstorage virtual machine (A2-DR) 524 corresponding to a replication ofthe storage virtual machine (A2) 514, which may provide failover accessto replicated user data in the event the storage cluster (A) 502experiences a disaster. The storage cluster (A) 502 may host areplicated storage virtual machine (B1-DR) 510 corresponding to areplication of the storage virtual machine (B1) 522, which may providefailover access to replicated user data in the event the storage cluster(B) 504 experiences a disaster.

FIG. 5A illustrates the storage virtual machine (A2) 514 activelyserving clients with access to user data of the storage aggregate (A2)stored within the second set of storage devices 534 (e.g., from withinstorage devices hosted at the storage cluster (A) 502, and where data isreplicated to mirrored storage devices hosted at the storage cluster (B)504) while the storage cluster (A) 502 has ownership 540 of the secondset of storage devices 534 and the storage aggregate (A2).

FIG. 5B illustrates a disaster 550 occurring at the storage cluster (A)502. The storage controller (A2) 516 may be inoperable for providingclients with access to user data through the storage aggregate (A2) ofthe storage virtual machine (A2) 514 because of the disaster 550.Accordingly, the relocation component 501 may perform a temporaryswitchover of ownership of the storage aggregate (A2) from the storagecluster (A) 502 to the storage cluster (B) 504 based upon a disasterrecovery relationship between the storage cluster (A) 502 and thestorage cluster (B) 504. FIG. 5C illustrates the relocation component501 switching ownership 540B of the second set of storage devices 534 ofthe storage aggregate (A2) from the storage cluster (A) 502 to thestorage cluster (B) 504. FIG. 5D illustrates the relocation component501 switching ownership of the storage aggregate (A2) from the storagecluster (A) 502 to the storage cluster (B) 504, which is illustrated bythe second set of storage devices 534 having the slanted line fill, asopposed to the dotted fill, to illustrate ownership by the storagecluster (B) 504. FIG. 5E illustrates the relocation component 501switching the replicated storage virtual machine (A2-DR) 524 from adormant state to an active state (e.g., where the replicated storagevirtual machine (A2-DR) 524 may remain to be owned by the storagecluster (A) 502) for providing failover client access to the storageaggregate (A2) that is temporarily owned by the storage cluster (B) 504.In this way, storage virtual machines may be switched over for failoveroperation to the storage cluster (B) 504 at a storage virtual machinelevel of granularity, which may improve a recovery time object (RTO)because merely some, but not all, of storage could be switched over inresponse to the disaster 550, for example.

FIG. 5F illustrates the relocation component 501 determining that thestorage cluster (A) 502 has recovered into an operational state from thedisaster 550. The relocation component 501 may switch the replicatedstorage virtual machine (A2-DR) 524 into the dormant state. Therelocation component 501 may switch ownership of the storage aggregate(A2) and the second set of storage devices 534 back from the storagecluster (B) 504 to the storage cluster (A) 502. In this way, therelocation component 501 may perform a switchback of ownership to thefirst storage cluster 502.

Still another embodiment involves a computer-readable medium comprisingprocessor-executable instructions configured to implement one or more ofthe techniques presented herein. An example embodiment of acomputer-readable medium or a computer-readable device that is devisedin these ways is illustrated in FIG. 6, wherein the implementation 600comprises a computer-readable medium 608, such as a CD-ft DVD-R, flashdrive, a platter of a hard disk drive, etc., on which is encodedcomputer-readable data 606. This computer-readable data 606, such asbinary data comprising at least one of a zero or a one, in turncomprises a set of computer instructions 604 configured to operateaccording to one or more of the principles set forth herein. In someembodiments, the processor-executable computer instructions 604 areconfigured to perform a method 602, such as at least some of theexemplary method 300 of FIG. 3, for example. In some embodiments, theprocessor-executable instructions 604 are configured to implement asystem, such as at least some of the exemplary system 400 of FIGS. 4A-4Dand/or at least some of the exemplary system 500 of FIGS. 5A-5F, forexample. Many such computer-readable media are contemplated to operatein accordance with the techniques presented herein.

It will be appreciated that processes, architectures and/or proceduresdescribed herein can be implemented in hardware, firmware and/orsoftware. It will also be appreciated that the provisions set forthherein may apply to any type of special-purpose computer (e.g., filehost, storage server and/or storage serving appliance) and/orgeneral-purpose computer, including a standalone computer or portionthereof, embodied as or including a storage system. Moreover, theteachings herein can be configured to a variety of storage systemarchitectures including, but not limited to, a network-attached storageenvironment and/or a storage area network and disk assembly directlyattached to a client or host computer. Storage system should thereforebe taken broadly to include such arrangements in addition to anysubsystems configured to perform a storage function and associated withother equipment or systems.

In some embodiments, methods described and/or illustrated in thisdisclosure may be realized in whole or in part on computer-readablemedia. Computer readable media can include processor-executableinstructions configured to implement one or more of the methodspresented herein, and may include any mechanism for storing this datathat can be thereafter read by a computer system. Examples of computerreadable media include (hard) drives (e.g., accessible via networkattached storage (NAS)), Storage Area Networks (SAN), volatile andnon-volatile memory, such as read-only memory (ROM), random-accessmemory (RAM), EEPROM and/or flash memory, CD-ROMs, CD-Rs, CD-RWs, DVDs,cassettes, magnetic tape, magnetic disk storage, optical or non-opticaldata storage devices and/or any other medium which can be used to storedata.

Although the subject matter has been described in language specific tostructural features or methodological acts, it is to be understood thatthe subject matter defined in the appended claims is not necessarilylimited to the specific features or acts described above. Rather, thespecific features and acts described above are disclosed as exampleforms of implementing at least some of the claims.

Various operations of embodiments are provided herein. The order inwhich some or all of the operations are described should not beconstrued to imply that these operations are necessarily orderdependent. Alternative ordering will be appreciated given the benefit ofthis description. Further, it will be understood that not all operationsare necessarily present in each embodiment provided herein. Also, itwill be understood that not all operations are necessary in someembodiments.

Furthermore, the claimed subject matter is implemented as a method,apparatus, or article of manufacture using standard applicationing orengineering techniques to produce software, firmware, hardware, or anycombination thereof to control a computer to implement the disclosedsubject matter. The term “article of manufacture” as used herein isintended to encompass a computer application accessible from anycomputer-readable device, carrier, or media. Of course, manymodifications may be made to this configuration without departing fromthe scope or spirit of the claimed subject matter.

As used in this application, the terms “component”, “module,” “system”,“interface”, and the like are generally intended to refer to acomputer-related entity, either hardware, a combination of hardware andsoftware, software, or software in execution. For example, a componentincludes a process running on a processor, a processor, an object, anexecutable, a thread of execution, an application, or a computer. By wayof illustration, both an application running on a controller and thecontroller can be a component. One or more components residing within aprocess or thread of execution and a component may be localized on onecomputer or distributed between two or more computers.

Moreover, “exemplary” is used herein to mean serving as an example,instance, illustration, etc., and not necessarily as advantageous. Asused in this application, “or” is intended to mean an inclusive “or”rather than an exclusive “or”. In addition, “a” and “an” as used in thisapplication are generally be construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform. Also, at least one of A and B and/or the like generally means A orB and/or both A and B. Furthermore, to the extent that “includes”,“having”, “has”, “with”, or variants thereof are used, such terms areintended to be inclusive in a manner similar to the term “comprising”.

Many modifications may be made to the instant disclosure withoutdeparting from the scope or spirit of the claimed subject matter. Unlessspecified otherwise, “first,” “second,” or the like are not intended toimply a temporal aspect, a spatial aspect, an ordering, etc. Rather,such terms are merely used as identifiers, names, etc. for features,elements, items, etc. For example, a first set of information and asecond set of information generally correspond to set of information Aand set of information B or two different or two identical sets ofinformation or the same set of information.

Also, although the disclosure has been shown and described with respectto one or more implementations, equivalent alterations and modificationswill occur to others skilled in the art based upon a reading andunderstanding of this specification and the annexed drawings. Thedisclosure includes all such modifications and alterations and islimited only by the scope of the following claims. In particular regardto the various functions performed by the above described components(e.g., elements, resources, etc.), the terms used to describe suchcomponents are intended to correspond, unless otherwise indicated, toany component which performs the specified function of the describedcomponent (e.g., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure. In addition, while aparticular feature of the disclosure may have been disclosed withrespect to only one of several implementations, such feature may becombined with one or more other features of the other implementations asmay be desired and advantageous for any given or particular application.

What is claimed is:
 1. A method, comprising: evaluating, by a storageserver, operational statistics of a first storage cluster and a secondstorage cluster to determine that the first storage cluster has a firstoperational load and that the second storage cluster has a secondoperational load, the first storage cluster comprising a first storagevirtual machine associated with a first storage aggregate and a secondstorage virtual machine associated with a second storage aggregate, thesecond storage cluster comprising a replicated storage virtual machinecorresponding to a replication of the first storage virtual machine; andresponsive to the first operational load being a threshold amountgreater than the second operational load: switching ownership of thefirst storage aggregate from the first storage cluster to the secondstorage cluster; switching ownership of the first storage virtualmachine and the replicated storage virtual machine from the firststorage cluster to the second storage cluster; and switching thereplicated storage virtual machine from a dormant state to an activestate for facilitating client access, from the second storage cluster,to user data stored through the first storage aggregate.
 2. The methodof claim 1, wherein the first storage cluster and the second storagecluster configured according to a disaster recovery relationship, thesecond storage cluster configured to provide failover client access todata, replicated from the first storage cluster, responsive to adisaster occurring at the first storage cluster.
 3. The method of claim2, wherein the first storage cluster comprising a third storageaggregate and a third storage virtual machine, the second storagecluster comprising a replicated third storage virtual machine that is areplication of the third storage virtual machine, and the methodcomprising: responsive to determining that the first storage cluster hasexperienced the disaster, performing a temporary switchover of ownershipof the third storage aggregate, but not the second storage aggregate,from the first storage cluster to the second storage cluster based uponthe disaster recovery relationship; and switching the third replicatedstorage virtual machine from the dormant state to the active state forproviding failover client access to the third storage aggregatetemporarily owned by the second storage cluster.
 4. The method of claim1, the switching ownership of the first storage aggregate comprising:utilizing a zero-copy ownership change operation to switch the ownershipof the first storage aggregate based upon replicated data within a localmirror storage device.
 5. The method of claim 1, comprising: maintainingnon-disruptive client access to data through the first storage aggregateduring switchover of ownership of the first storage aggregate, the firststorage virtual machine, and the replicated storage virtual machine fromthe first storage cluster to the second storage cluster.
 6. The methodof claim 1, the switching ownership of the first storage aggregatecomprising: unmounting the first storage aggregate; changing ownershipof a first storage device, associated with the first storage aggregate,from the first storage cluster to the second storage cluster; andonlining the first storage aggregate for ownership by the second storagecluster.
 7. A non-transitory machine readable medium having storedthereon instructions for performing a method comprising machineexecutable code which when executed by at least one machine, causes themachine to: evaluate operational statistics of a first storage clusterand a second storage cluster to identify a set of load balancingmetrics; permanently change ownership of one or more storage aggregatesand one or more storage virtual machines between the first storagecluster and the second storage cluster utilizing zero-copy ownershipchange operations based upon the set of load balancing metrics; andfacilitate client access to the one or more storage aggregates basedupon the ownership change.
 8. A comprising device comprising: a memorycontaining machine readable medium comprising machine executable codehaving stored thereon instructions for performing a method of storagevirtual machine relocation; and a processor coupled to the memory, theprocessor configured to execute the machine executable code to cause theprocessor to: evaluate operational statistics of a first storage clusterand a second storage cluster to determine that the first storage clusterhas a first operational load and that the second storage cluster has asecond operational load, the first storage cluster comprising a firststorage virtual machine associated with a first storage aggregate and asecond storage virtual machine associated with a second storageaggregate, the second storage cluster comprising a replicated storagevirtual machine corresponding to a replication of the first storagevirtual machine; and responsive to the first operational load being athreshold amount greater than the second operational load: switchownership of the first storage aggregate from the first storage clusterto the second storage cluster; switch ownership of the first storagevirtual machine and the replicated storage virtual machine from thefirst storage cluster to the second storage cluster; and switch thereplicated storage virtual machine from a dormant state to an activestate for facilitating client access, from the second storage cluster,to user data stored through the first storage aggregate.
 9. Thecomputing device of claim 8, wherein the machine executable code causesthe processor to: unmount the first storage aggregate; change ownershipof a first storage device, associated with the first storage aggregate,from the first storage cluster to the second storage cluster; and onlinethe first storage aggregate for ownership by the second storage cluster.10. The computing device of claim 8, wherein the machine executable codecauses the processor to: utilize a zero-copy ownership change operationto switch the ownership of the first storage aggregate based uponreplicated data within a mirror storage device.
 11. The computing deviceof claim 10, wherein the mirror storage device configured as a backupmirror of data stored within a first storage device associated with thefirst storage aggregate.
 12. The computing device of claim 8, whereinthe machine executable code causes the processor to: switch the firststorage virtual machine from the active state to the dormant state. 13.The computing device of claim 8, wherein the machine executable codecauses the processor to: specify that the second storage cluster is anon-temporary owner of at least one of the first storage aggregate, thefirst storage virtual machine, or the replicated storage virtualmachine.
 14. The computing device of claim 8, wherein the machineexecutable code causes the processor to: maintain non-disruptive clientaccess to data through the first storage aggregate during switchover ofownership of the first storage aggregate, the first storage virtualmachine, and the replicated storage virtual machine from the firststorage cluster to the second storage cluster.
 15. The computing deviceof claim 8, wherein the first storage cluster and the second storagecluster configured according to a disaster recovery relationship, thesecond storage cluster configured to provide failover client access todata, replicated from the first storage cluster, responsive to adisaster occurring at the first storage cluster.
 16. The computingdevice of claim 15, wherein the first storage cluster comprising a thirdstorage aggregate and a third storage virtual machine, the secondstorage cluster comprising a replicated third storage virtual machinethat is a replication of the third storage virtual machine, and therelocation component configured to: responsive to determining that thefirst storage cluster has experienced the disaster, perform a temporaryswitchover of ownership of the third storage aggregate, but not thesecond storage aggregate, from the first storage cluster to the secondstorage cluster based upon the disaster recovery relationship.
 17. Thecomputing device of claim 16, wherein the machine executable code causesthe processor to: switch the third replicated storage virtual machinefrom the dormant state to the active state for providing failover clientaccess to the third storage aggregate temporarily owned by the secondstorage cluster.
 18. The computing device of claim 17, wherein themachine executable code causes the processor to: responsive todetermining that the first storage cluster has recovered to anoperational state from the disaster, perform a switchback of ownershipof the third storage aggregate from the second storage cluster to thefirst storage cluster.
 19. The computing device of claim 18, wherein themachine executable code causes the processor to: switch the thirdreplicated storage virtual machine from the active state to the dormantstate based upon the switchback.
 20. The computing device of claim 8,wherein the relocation component configured to: permanently changeownership of one or more storage aggregates and one or more storagevirtual machines between the first storage cluster and the secondstorage cluster utilizing zero-copy ownership change operations basedupon load balancing metrics associated with the first storage clusterand the second storage cluster.